I'm not asking them to make available the exact same code; nothing says they have to make RHEL available to anyone other than their customers. It's conventional in the open source world to do so, but not required, and they've chosen not to because they have this business model of selling GPL software and making it difficult to obtain for free what they're selling.

Trying to make a profit through that business model is fine. Having that as their business model doesn't give them the right to violate the license though. They are threatening their customers if their customers exercise their right to redistribute RHEL (with the apparent goal of making RHEL, the exact product, difficult to obtain for anyone other than their customers -- basically building on other people's work for free, without honoring the terms of free redistribution under which those people made their work available to Redhat for free).

In GPL v2, the relevant text is in section 6:

You may not impose any further restrictions on the recipients' exercise of the rights granted herein.